1. Field of the Invention
This invention relates to an electronic thermometer employing infrared radiation, and more particularly to an ear type clinical thermometer that detects an infrared radiation quantity radiated from a tympanum to measure body temperature.
2. Description of the Related Art
As shown in FIG. 1, there is well known an ear type clinical thermometer having a probe (an infrared radiation input unit) 1 mounted by a probe cover 2 for stain or contagion protection on measurement. In such a conventional clinical thermometer, infrared radiation passing through the probe 1 is detected by an infrared radiation sensor 3, and applied to a CPU (central processing unit) 5 through an A/D (analog-to-digital) converter 4. Internal temperature of the clinical thermometer is detected by a temperature sensor 6, and applied to the CPU 5 through the A/D converter 4 in the same way. The CPU 5 detects temperature or body temperature based on the detected infrared radiation quantity and internal temperature to be indicated by a display 7. In this kind of clinical thermometer, attenuation of infrared radiation by the probe cover 2 is considered to detect the temperature from the infrared radiation quantity detected by the infrared radiation sensor 3. The conventional ear type clinical thermometer is designed to set a computation expression to correctly measure body temperature when the probe cover is mounted, but has a problem to indicate an abnormal measurement result when temperature is measured without mounting any probe cover.
It is, therefore, a primary object of this invention to provide an electronic thermometer capable of precisely measuring temperature such as body temperature without affection by the presence or absence of a probe cover nor by the kind of the probe cover.
According to this invention, there is provided an electronic thermometer including a probe to be inserted in to a portion of an outer ear to be measured by the thermometer, an infrared quantity detection means for detecting an infrared radiation quantity which is entered through the probe, a temperature computation means for applying the detected infrared radiation quantity in a predetermined computation expression to compute out temperature such as body temperature, an infrared transmission data reading means for taking data corresponding to an infrared transmission quantity passing through the probe, and a control means for controlling the computation expression according to the taken data corresponding to the infrared transmission quantity.
The taken data corresponding to the infrared radiation transmission quantity includes, in addition to the data of an infrared radiation quantity having passed the probe, data of an infrared radiation quantity to be passed through the probe, and data correlating to these transmitted infrared radiation quantities. In this electronic thermometer, for instance, an infrared radiation quantity entering through the probe from a tympanum is detected by the infrared quantity detection means, and temperature (body temperature) is computed out by the temperature computation means according to a predetermined computation expression based on the detected infrared radiation quantity. The data corresponding to the infrared radiation quantity is taken by infrared quantity detection means, the computation expression is controlled by the taken data, for instance, constants are revised. Accordingly, even if an infrared radiation transmission quantity by the probe is different, right temperature (body temperature) can be measured by doing compensation by the difference.